A wide variety of electrical cables are available on the market and they range from straightforward constructions having a single conductor through to more complex constructions having, for example, multiple conductors, a co-axial conductor arrangement or shielded subsets of conductors. Some cables are intended for use in quite specific applications and when designing such cables a number of factors need to be taken into consideration. These include the characteristics of the electrical current or signal that the cable needs to convey and the intended environmental conditions that the cable will need to operate within. Other factors relate to the more mechanical aspects of the cable such as how flexible it needs to be, whether it should be compatible with particular post-manufacture processes and even it's visual appearance and feel.
Traditionally, the electronics industry and the clothing industry have produced products in different fields and have remained apart. More recently, a joint project between Philips Electronics and Levi Strauss® culminated in the launch of the Levi's ICD+jacket range in 2000. The jackets of this range were designed to carry a mobile telecommunications device, portable audio device (an MP3 player), user headphones and a microphone. The jackets were also provided with wiring to connect these devices together and a user keypad for controlling the devices and providing added functionality in terms of synchronising device operation.
The Levi's ICD+jackets are an example of non-rigid items which require a component part, in this case an electrical cable, more generally associated with the electrical or electronics industry than with the clothing industry. However, while such cable or cabling must be able to perform the function of conveying electrical current or signals, it's use in a garment requires the cable to have other characteristics. Such a cable should be flexible enough to bend with the garment during use and be sufficiently discrete such that even when the cable is located beneath the exterior surface of the garment, the presence of the cable does not detract from the appearance or hang of the garment. Furthermore, the presence of the cable should not cause discomfort to the person using the garment. Some of these characteristics are also desirable when cabling is fitted to other items such as clothing accessories, soft furnishings or other fabric based ‘soft’ items.
Some known attempts to provide electrical current or signal carrying conductors in fabric based articles have been based on standard ‘flat’ textile structures of woven or knitted layers. The conductors are provided by including conductive yarns during the knitting or weaving process or by applying conductive layers to the yarn at a later stage. These approaches lead to arrangements occupying relatively large surface areas, especially when there is a need to separate multiple conductors, and difficulties with reliably insulating and isolating selected parts of the circuitry that the conductors form. It can also be difficult to provide shielding for these arrangements, as is often required to minimise electromagnetic emission or the effects of external interference.
It is an object of the present invention to provide an electrical cable which is suitable for including in items such as garments, clothing accessories, soft furnishings, upholstered articles and other such ‘soft’ items.